1. Field of the Invention
The present invention relates to an insertion apparatus used with an endoscope having a flexible insertion section, such as a biopsy forceps and a clip insertion apparatus.
2. Description of the Related Art
Jpn. Pat. Appln. KOKAI Publication No. 8-280701 discloses an insertion apparatus used with an endoscope having a flexible insertion section. An insertion apparatus, such as a biopsy forceps and a clip insertion apparatus, has an insertion portion including an outer tube (tubular member) 120 which is a metallic coil made of stainless steel for example, and a control wire 130 which is inserted into the outer tube 120 and made by a thin metallic single wire or twisted wire connected to a surgical tool at the distal end, as shown in FIG. 23 and FIG. 24. The control wire 130 includes a hook unit 131 to engage with a surgical tool such as a clip unit, and a wire 132. A cylindrical connection member 131b is provided between the hook unit 131 and wire 132. It is necessary to pull an operation member such as the control wire 130 with respect to the outer tube 120 by a strong force, in order to operate a surgical tool provided at or engaged with the end of the control wire 130.
To be formed along the curve of an insertion section of an endoscope or to have a structure easy to operate, it is common to form the outer tube 120 by connecting two coils 122 and 124 (refer to FIG. 23) in the distal end side and proximal end side, and to make the distal end coil 122 more flexible than the proximal end coil 124. In the outer tube 120, the proximal end of the distal end coil 122 and the distal end of the proximal end coil 124 thicker and smaller in diameter than the distal end coil 122 are directly connected by laser welding, for example. In addition to the above, the control wire 130 is generally formed by connecting two wires, to make the distal end side more flexible than the proximal end side.
The above configuration realizes the flexibility adaptable to the bending of a flexible endoscope, while providing the outer tube 120 bearable to a strong pulling force.